package net.ix.movable;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.Scroller;

public class TouchTest extends ViewGroup{
	@SuppressWarnings("unused")
	private static String TAG = "TouchTest";
	
	private Scroller mScroller;
	private VelocityTracker mVelocityTracker;
	
	private int mCurScreen;
	private int mDefaultScreen;
	
	private static final int TOUCH_STATE_REST = 0;
	private static final int TOUCH_STATE_SCROLLING = 1;
	private static final int SNAP_VELOCITY = 600;
	
	private int mTouchState = TOUCH_STATE_REST;
	private int mTouchSlop;
	private float mLastMotionX;
	private float mLastMotionY;
	
	public TouchTest(Context context, AttributeSet attrs){
		this(context, attrs, 0);
	}
	public TouchTest(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		
		mScroller = new Scroller(context);
		mCurScreen = mDefaultScreen;
		mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
	}
	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		if(changed){
			int childLeft = 0;
			final int childCount = getChildCount();
			
			for(int i = 0; i < childCount; i++){
				final View childView = getChildAt(i);
				if(childView.getVisibility() != View.GONE){
					final int childWidth = childView.getMeasuredWidth();
					childView.layout(childLeft, 0, childLeft + childWidth, childView.getMeasuredHeight());
					childLeft += childWidth;
				}
			}
		}
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		Log.e(TAG, "onMeasure");
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		final int width = MeasureSpec.getSize(widthMeasureSpec);
		final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
		if (widthMode != MeasureSpec.EXACTLY) {
			throw new IllegalStateException(
					"ScrollLayout only canmCurScreen run at EXACTLY mode!");
		}
		final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
		if (heightMode != MeasureSpec.EXACTLY) {
			throw new IllegalStateException(
					"ScrollLayout only can run at EXACTLY mode!");
		}
		// The children are given the same width and height as the scrollLayout
		final int count = getChildCount();
		for (int i = 0; i < count; i++) {
			getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
		}
		// Log.e(TAG, "moving to screen "+mCurScreen);
		scrollTo(mCurScreen * width, 0);
	}
	/**
	 * 
	 * According to the position of current layout
	 * 
	 * scroll to the destination page.
	 */
	public void snapToDestination() {
		final int screenWidth = getWidth();
		final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth;
		snapToScreen(destScreen);
	}

	public void snapToScreen(int whichScreen) {
		// get the valid layout page
		whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
		if (getScrollX() != (whichScreen * getWidth())) {
			final int delta = whichScreen * getWidth() - getScrollX();
			mScroller.startScroll(getScrollX(), 0,
			delta, 0, Math.abs(delta) * 2);
			mCurScreen = whichScreen;
			invalidate(); // Redraw the layout
		}
	}

	public void setToScreen(int whichScreen) {
		whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1));
		mCurScreen = whichScreen;
		scrollTo(whichScreen * getWidth(), 0);
	}

	public int getCurScreen() {
		return mCurScreen;
	}
	
	@Override
	public void computeScroll() {
		// TODO Auto-generated method stub
		if (mScroller.computeScrollOffset()) {
			scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
			postInvalidate();
		}
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub
		if (mVelocityTracker == null) {
			mVelocityTracker = VelocityTracker.obtain();
		}

		mVelocityTracker.addMovement(event);
		final int action = event.getAction();
		final float x = event.getX();
		final float y = event.getY();
		switch (action) {
		case MotionEvent.ACTION_DOWN:
			Log.e(TAG, "event down!");
			if (!mScroller.isFinished()) {
				mScroller.abortAnimation();
			}
			mLastMotionX = x;
			Log.i(TAG, "SX: " + this.getScrollX());
			Log.i(TAG, "W: " + this.getWidth());
			Log.i(TAG, "C: " + this.getChildCount());
			break;
		case MotionEvent.ACTION_MOVE:
			int deltaX = (int) (mLastMotionX - x);
			mLastMotionX = x;
			if((deltaX + getScrollX()) < (getChildCount()-1) * getWidth() && (deltaX + getScrollX()) > 0){
				scrollBy(deltaX, 0);
			} //else if ((deltaX + getScrollX()) >= (getChildCount()-1) * getWidth()){
				//scrollBy((getChildCount()-1) * getWidth(), 0);
			//} else if ((deltaX + getScrollX()) <= 0) {
				//scrollBy(0, 0);
			//}
			break;
		case MotionEvent.ACTION_UP:
			Log.e(TAG, "event : up");
			// if (mTouchState == TOUCH_STATE_SCROLLING) {
			final VelocityTracker velocityTracker = mVelocityTracker;
			velocityTracker.computeCurrentVelocity(1000);
			int velocityX = (int) velocityTracker.getXVelocity();
			Log.e(TAG, "velocityX:" + velocityX);
			if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
				// Fling enough to move left
				Log.e(TAG, "snap left");
				snapToScreen(mCurScreen - 1);
			} else if (velocityX < -SNAP_VELOCITY
			&& mCurScreen < getChildCount() - 1) {
				// Fling enough to move right
				Log.e(TAG, "snap right");
				snapToScreen(mCurScreen + 1);
			} else {
				snapToDestination();
			}
//			if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
//
//				// Fling enough to move left
//
//				Log.e(TAG, "snap left");
//				if (mCurScreen > getChildCount() - 1) {
//					View v1 = getChildAt(0);
//					View v2 = getChildAt(1);
//					View v3 = getChildAt(2);
//					
//				}
//				snapToScreen(mCurScreen - 1);
//
//			} else if (velocityX < -SNAP_VELOCITY
//
//			&& mCurScreen < getChildCount() - 1) {
//
//				// Fling enough to move right
//
//				Log.e(TAG, "snap right");
//
//				snapToScreen(mCurScreen + 1);
//
//			} else {
//
//				snapToDestination();
//
//			}
//
//			if (mVelocityTracker != null) {
//
//				mVelocityTracker.recycle();
//
//				mVelocityTracker = null;
//
//			}

			// }
			mTouchState = TOUCH_STATE_REST;
			break;
		case MotionEvent.ACTION_CANCEL:
			mTouchState = TOUCH_STATE_REST;
			break;
		}
		return true;
	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
		// TODO Auto-generated method stub
		Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop + "; action = " + ev.getAction());
		final int action = ev.getAction();
		if ((action == MotionEvent.ACTION_MOVE) &&
		(mTouchState != TOUCH_STATE_REST)) {
			Log.e(TAG, "onInterceptTouchEvent-action:" + action);
			return true;
		}
		final float x = ev.getX();
		final float y = ev.getY();

		switch (action) {
		case MotionEvent.ACTION_MOVE:
			final int xDiff = (int) Math.abs(mLastMotionX - x);
			Log.e(TAG, "onInterceptTouchEvent-move: xDiff = " + xDiff + "; mLastMotionX = " + mLastMotionX);
			if (xDiff > mTouchSlop) {
				mTouchState = TOUCH_STATE_SCROLLING;
			}
			break;
		case MotionEvent.ACTION_DOWN:
			mLastMotionX = x;
			mLastMotionY = y;
			Log.e(TAG, "onInterceptTouchEvent-down: x = " + x + "; y = " + y);
			mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST
					: TOUCH_STATE_SCROLLING;

			break;
		case MotionEvent.ACTION_CANCEL:
		case MotionEvent.ACTION_UP:
			Log.e(TAG, "onInterceptTouchEvent-up: mLastMotionX = " + mLastMotionX);
			mTouchState = TOUCH_STATE_REST;
			break;
		}
		return mTouchState != TOUCH_STATE_REST;
	}
}